1. Field of the Invention
This invention relates to equipment for unloading petroleum products such as diesel fuel from one storage or transport tank to another, such as from a railcar to a transport trailer, and more particularly, to a portable system for unloading a railcar into a transport trailer without the necessity of any permanently installed equipment and which can be used at virtually any site at which access to the railcar is available.
2. Brief Description of the Prior Art
The use of railroad tank cars for bulk transportation of petroleum products, such as diesel and other fuels, is well known. It is also known to transport such fluids over the highways by truck using specially designed transport trailers, often called tanker trailers.
The railcars have top openings therein through which the railcars can be filled or loaded and bottom openings through which they can be emptied or unloaded. A valve on the bottom opening is used to open and close it. Normally, loading the railcar is done at a refinery site. When the railcars travel to an unloading terminal, permanent equipment is used to unload the railcar and transfer the product therein to another vessel of some sort. This might be a stationary storage tank, but often is a transport trailer. Both the stationary tanks and the tanks on the transport trailers also have openings therein with valves controlling them through which these vessels can be loaded and subsequently unloaded. It is not uncommon for these tanks to have separate compartments for different products, for example, diesel fuel and gasoline. Separate openings and valves are used for the different compartments.
When transferring a liquid such as diesel fuel, the previously mentioned permanent system is used. Such a permanent system includes a pump, usually driven by an explosion-proof electric motor and a meter downstream of the pump to measure and frequently record the amount of fuel transferred. An inlet hose is connected between inlet piping to the pump and the valve on the railcar, and an outlet hose is connected between outlet piping from the meter and the desired valve on the transport trailer. These hoses may have grounding wires woven therein so that when they are connected to metal piping, valves, etc., the chance of static electricity is minimized. This is necessary because a small spark could ignite the products being transferred or at least vapors therefrom.
In these prior art permanent installations, obviously it is necessary to take the transport trailer to the terminal to which the railcars have been brought. The unloading of the product from the railcar cannot take place anywhere else. Therefore, if it is desired to unload the railcar at any other site, the permanent system is unusable. Thus, there is a need for a system which can be used to transfer product from a railcar when it is parked at a site which does not have an unloading terminal located there. The present invention solves this problem by providing a portable transferring and unloading system mounted in a small trailer which can be taken to virtually any site at which a transport trailer can be located near the railcar.
In permanent installations, although some lengths of hoses are used, most of the piping is fixed, and it does not matter if fluids remain therein after a transferring or pumping cycle. Any spillage is caught in permanent areas around the system. In the portable system of the present invention there is a relatively small amount of fixed piping in the trailer, and most of the connections between the railcar and the transport trailer are with flexible hoses. When the pumping is done, the outlet hose will still be full of fluid. After disconnecting such a hose, the hose would be extremely heavy and difficult to handle and there would be spillage of some, if not most, of the liquid in the hose. This not only would waste valuable product, such as diesel fuel, but such spills would be detrimental to the environment and most likely would violate environmental laws or regulations. The present invention solves this problem by providing a connection in the outlet of the system whereby pressurized air from the truck is used to blow the remaining liquid out of the outlet hose and into the transport trailer.
In today's petroleum market, prices can fluctuate significantly depending on economic and world conditions and events. Marketers of petroleum products, such as diesel fuel, want to find the fuel at the least possible price in order to have a competitive advantage, or at least to be competitive with other marketers. Often, a lower price might be found at some distance away from the marketer's normal supply point. In such cases, marketers may take their transport trucks to those more remote locations to load with petroleum products if the cost of transportation is not prohibitive. This still requires the transport truck to be taken to a terminal where railcars are being unloaded, and this may add more cost than can be absorbed by the marketer. Also, even once at the terminal, it may take some time for a particular transport truck to be filled if a number are waiting. If unloading could be speeded up, this would be an advantage for everyone. Further, sometimes the railcars are still at a siding somewhere and not yet located at a terminal, and currently, this means they cannot be unloaded until they are moved to a terminal. This may result in a time delay which increases the cost of transportation for the suppliers who move the products by rail. If railcars could be unloaded earlier, the supplier would get paid sooner, and the railcar could be turned around more quickly to be reloaded. Also, if unloading could be accomplished more quickly, marketers might be able to buy it at a lower price and get the petroleum into the marketing stream earlier. All of this would improve cash flow at all levels of the petroleum market, from the supplier to retail consumers.
The present invention provides such an economic improvement because it can be used by the marketer to unload railcars and load transport trucks more quickly at terminals and even do this where there is no terminal because the inventive system is portable and self-contained.